Figure 1.

Scanning electron microscopy of bone surfaces. Periosteal surfaces of wild-type (A) and D4 transgenic (B) femurs corresponding to the area of the diaphysis bracketed in panel C. The third trochanter is located at the top of both micrographs. Osteoclastic resorption lacunae are absent from the diaphyseal surfaces of both bones and are only visible distal to the third trochanter in the transition to the distal metaphysis (asterisk in panel A). The transition zone between diaphysis and metaphysis in the D4 bone (boxed in panel B) is shown at higher magnification in panel D. The resorptive surface of the metaphysis (r) is clearly distinct from the diaphysis, which has the characteristic appearance of forming and mineralizing bone (f). These micrographs also revealed a dramatic increase in the size of the vasculature in D4 bone compared with wild-type. One vascular pore is indicated with an arrow in panel D. The mineralizing surface in D4 bone appears somewhat disorganized compared with the wild-type surface, consistent with the irregular cross-sectional appearance of fluorochrome labels in D4 bone (Erlebacher and Derynck, 1996). Osteocyte lacunae are indicated with arrowheads in panel D. Scale bars, 200 μm in A and B; 100 μm in D.